Projects

UKAI

Background

Virtualization technology make various kind of services
more flexible to scale out and scale down whenever necessary
which was difficult when physical computers were used as components
of services. Operation of a virtual infrastructure requires
flexible resource location and relocation mechanism treating virtual
machines as one of the managed resources.

The technology to migrate CPU and memory resources are mature enough,
and migration of network functions is now intensively researched.
The final issue of resource migration is a storage resource migration.

We are working on a storage system "UKAI" which is
applicable for a wide area datacenter operation
to enable flexible location and relocation of virtual machines.
By using UKAI, operators can control redundancy of a virtual disk
and the location of the contents of the virtual disk as they intend.

Basic Idea

Each virtual machine has its virtual disk. In the UKAI system,
a virtual disk is represented as a set of pointers to the real
contents.

A virtual disk is divided into several logical blocks. The
content of each block is stored in a separate storage node.
By using multiple storage nodes, operators can increase of decrease
redundancy level based on the required robustness.

The figure below depicts a sample configuration using three
storage nodes and each block has two replicated contents.

Storage Migration

When a virtual machine migrates to another hypervisor,
the access to its storage contents may become slower based on the
location of the new hypervisor.

In the UKAI system, an operator can migrate a virtual disk
by creating a new copy of the disk near the new hypervisor and
removing the old contents.